In the related art, for example, a ceramic honeycomb structure having a plurality of through-holes having a polygonal cross-sectional shape has been known. The honeycomb structure is used in a diesel particulate filter, and the like. The honeycomb structure is produced by molding a ceramic raw material powder by an extruding method and the like to prepare a green honeycomb molded body, cutting the green honeycomb molded body to have a desired length, closing the green honeycomb molded body, and calcining the green honeycomb molded body. As a method for closing the green honeycomb molded body, for example, as disclosed in Patent Literature 1, a method for using a pressing jig for closing is suggested. The pressing jig for closing which is disclosed in Patent Literature 1 has a pin-holder shape including a heater unit and a plurality of needles which protrude from the heater unit, and the plurality of needles can be heated by the heater unit. In addition, the plurality of needles are constituted by a straight portion having a square cross-sectional shape, and a tip end portion which is formed at the tip end of the straight portion and has a pyramid shape. In addition, in a state in which the plurality of needles are heated by the heater unit, the plurality of needles are inserted into through-holes of the green honeycomb molded body to deform the through-holes, thereby closing the through-holes.